Kevin Kelley has created a PPA with Emacs 25 packages for all current Ubuntu releases. A patch was made into the packages to fix for an `xinput`-related bug that, when triggered, causes `emacs` to enter an infinite loop; the process will then be unresponsive and will consume 100% of a single CPU core until you kill it.

1. Open terminal by pressing Ctrl+Alt+T or searching for “Terminal” from start menu. When it opens, run command to add the PPA:

sudo add-apt-repository ppa:kelleyk/emacs

Type in your password (no visual feedback due to security reason) when prompts and hit Enter.

2. Then update and install Emacs 25 via commands:

sudo apt update
sudo apt install emacs25

For text-only interface, replace emacs25 with emacs25-nox in the last command.

Don’t know why, but I need to log out and back in to be able to launch Emacs 25 from the Dash.

How to Remove:

To remove Emacs25, open terminal and run commands:

sudo apt remove emacs25 emacs25-nox && sudo apt autoremove

The PPA can be removed by going to System Settings -> Software & Updates -> Other Software tab.